The present invention relates generally to the system control art and related communication between controlling apparatus and controlled apparatus in such systems. More particularly, the present invention relates to communication systems for use in industrial, or other, control systems, including heating, ventilating, and air conditioning (HVAC) systems. In its preferred embodiment, the present invention provides an infrared communication system with associated hardware and a communication protocol for use in an HVAC or other control system.
Control systems are well established and well known in a variety of applications. Likewise, a variety of control systems are presently utilized for HVAC control applications. Typically, such systems comprise a plurality of remote points, such as blowers, ventilators and thermostats, associated with a common controlling unit. In such systems, a base controller monitors the conditions at the various remote points and issues instructions to those points or other points in response to changes in the conditions being monitored or in response to instructions entered at the base controller.
HVAC control systems also face a variety of common problems. Initially, there is a large cost in the installation and wiring for each of the remote points, even in a single room. In a central room containing air conditioning and heating equipment, the additional wiring and remote point sensors can add undesirably to the clutter. Maintenance costs similarly can be amplified when hardwired sensors need to be checked or repaired. The wide variation among the types of equipment utilized in any one system, e.g., ventilator motors, servos, thermostats or other temperature gauges, also can present maintenance, cost and installation obstacles. Finally, electromagnetic noise frequently generated in the starting and stopping of various motors used in the HVAC or other systems can create undesirable noise in the hardwire communication with the base controller, as these lengthy wires may act as antennas. This can be particularly troublesome in an HVAC application, because erroneous temperature readings and/or circulation settings can lead quickly to physically uncomfortable environments for those in the controlled building.